Sonographic detection of occult fractures in the foot and ankle

Purpose. The purpose of this retrospective study was to determine whether h igh-resolution sonography can aid in the diagnosis of radiographically occu lt fractures in the foot and ankle. Methods. High-resolution sonography with a 10-MHz linear-array transducer w as performed in 268 patients with foot and ankle injuries whose initial pla in x-ray films were negative for fracture. Results. Twenty-four patients had occult fractures demonstrated by sonograp hy. On sonography, the occult fractures appeared as a discontinuity of cort ex echogenicity. The fractures were found at the calcaneus (n = 8), metatar sus (n = 6), talus (n = 3), navicular bone (n = 3), cuboid bone (n = 2), cu neiform bone (n = 1), and lateral malleolus (n = 1). Review of the patients ' radiographs revealed ti ny fractures at the sonographically identified lo cations in 2 patients. The first 5 patients underwent bone scans, which con firmed the presence of the fractures. The first 11 patients received follow -up sonographic examination 6 weeks after diagnosis; in all 11, an echogeni c line over the previous fracture site, presumably representing callus form ation, was noted. Conclusions. Sonography-a readily available, noninvasive imaging technique- can provide important information about soft tissue injuries and cortical d iscontinuities in the foot and ankle area. Using this procedure, occult fra ctures can be identified and delineated, and costly procedures such as MRI can be avoided. (C) 1999 John Wiley & Sons, Inc.